The present invention relates to a heavy oil fired boiler exhaust gas treatment apparatus.
Conventionally, as shown in FIG. 4, as a treatment method for SO3 in exhaust gas of a heavy oil fired boiler 401, there has generally been used a method in which a salt such as ammonium sulfate ((NH4)2SO4) is yielded by pouring a neutralizer such as ammonia on the upstream side of an electric dust collector 402, and the SO3 is trapped together with soot and dust by the electric dust collector 402. The exhaust gas passes through a wet type exhaust gas desulfurizer 403 and is discharged from a stack 405. When far higher dust removing performance is required, a wet type electric dust collector 404 is installed on the downstream side of the wet type exhaust gas desulfurizer 403 to effect high-level dust removal.
However, a neutralizing salt yielded by the pouring of a neutralizer consists of fine particles, so that it is difficult to trap the neutralizing salt by the electric dust collector 402 and an absorption tower of the desulfurizer 403. Further, since ammonium sulfate is trapped as part of soot and dust together with soot and dust in the electric dust collector 402, the capacity of the electric dust collector 402 must be increased. Therefore, the conventional method poses a problem in that not only the site area but also the installation cost and operation cost increase.
Thereupon, a heavy oil fired boiler exhaust gas treatment apparatus which solves above problems has been desired.
The present invention has been made in view of the above situation, and accordingly an object thereof is to provide a heavy oil fired boiler exhaust gas treatment apparatus which removes soot and dust and SO3 in the heavy oil fired boiler exhaust gas efficiently at a low cost without using an excessively large apparatus.
To solve the above problems, the present invention provides a heavy oil fired boiler exhaust gas treatment apparatus comprising a charging device provided at the inlet of an absorption tower of a wet type exhaust gas desulfurizer and neutralizer pouring means provided on the upstream side of the charging device for pouring a neutralizer into exhaust gas and for neutralizing SO3 in the exhaust gas.
Also, the present invention provides a heavy oil fired boiler exhaust gas treatment apparatus comprising an electric dust collector for collecting dust in exhaust gas sent from a heavy oil fired boiler, neutralizer pouring means provided on the upstream side of the electric dust collector for pouring a neutralizer into the exhaust gas and for neutralizing SO3, and a wet type exhaust gas desulfurizer, wherein a charging device is provided at the inlet of an absorption tower of said wet type exhaust gas desulfurizer.
In a heavy oil fired boiler exhaust gas treatment apparatus according to the present invention, an accelerating dust collector may be provided at the outlet of the absorption tower.
In a heavy oil fired boiler exhaust gas treatment apparatus according to the present invention, there may be provided a spray for spraying water into the exhaust gas on the upstream side of an accelerating dust collector.
In a heavy oil fired boiler exhaust gas treatment apparatus according to the present invention, there may be provided separator for separating unburned carbon from an absorbent liquid obtained from the absorption tower.
In a heavy oil fired boiler exhaust gas treatment apparatus according to the present invention, there may be provided means for separating and recovering a neutralizer in an absorbent liquid drawn from an oxidation tank of the wet type exhaust gas desulfurizer.
In a heavy oil fired boiler exhaust gas treatment apparatus according to the present invention, a high-pressure spray may be provided immediately behind the charging device.
As is apparent from the above description, according to the present invention, there is provided a heavy oil fired boiler exhaust gas treatment apparatus which removes soot and dust and SO3 in the heavy oil fired boiler exhaust gas efficiently at a low cost without using an excessively large apparatus.
That is, according to the present invention, by installing a charging device, soot and dust (containing a neutralizing salt such as ammonium sulfate) are charged. Further, by installing a high-pressure (pressurized) spray, tiny water drops can be sprayed, by which fine particles can be agglomerated and enlarged. Thereby, soot and dust can be trapped in the absorption towers with high efficiency.
When an accelerating dust collector is installed, soot and dust can be recovered efficiently, so that an electric dust collector, which requires a high cost, can be omitted or made compact.
Further, when a liquid cyclone and means for separating and recovering a neutralizer are installed, unburned carbon and neutralizer trapped in the absorption towers can be recovered, so that the usage can be reduced. Therefore, the heavy oil fired boiler exhaust gas treatment apparatus can be improved as a whole.